| 摘要 |
PURPOSE:To accurately and correctly adjust toner concentration according as a carrier secularly deteriorates by shifting a detecting output from a toner sensor stepwise according as a developer secularly changes in the toner concentration, etc., due to lowering in the fluidity of the developer, etc. CONSTITUTION:A control voltage Vc to be impressed on a toner sensor 1 is shifted down stepwise according as the carrier secularly deteriorates. Namely, when the toner in a toner replenishing device 4 is consumed by plural printings, a toner cartridge 10 is replaced and the toner is replenished again. The number of the cartridges 10 is previously set according to the toner consumption when the actual toner concentration reaches near the upmost control level according as the carrier deteriorates. When the set number of cartridges 10 are replaced, the control voltage Vc which is impressed on the toner sensor 1 is shifted down. Thus, the toner concentration can be accurately and correctly controlled according to the actual toner concentration level. |
